Megan Fox’s “Vampire Baby”

“The first trimester was really rough and then I got to about 12 weeks and then it was fine,” the actress, 26, said. “It was really a perfect pregnancy after that.”

And the last time she sat down with Jay, she was hiding a barely-there baby bump.

“I was about two months pregnant. I was really sick,” the star of This Is 40 actress said of her February appearance. “I was very nauseous. I had really bad morning sickness.”

“It was so bad for me. . . I was convinced that I was, like, maybe birthing a vampire baby like the one in Twilight — you know what happens to Bella, where she’s in cold sweats all the time — and I felt like that was happening because I had no vitamins and nutrients and I was just nauseous,” she continued.

“Something not human was happening!” she joked.

And she opened up about the September 27 birth of her son Noah Shannon.

“I thought I was going to be tough and the nurses would be like, ‘She’s a warrior princess! She doesn’t need an epidural! She’s amazing! We’re such big fans!’” she admitted. “As soon as I got out of the car I was already crying for an epidural. I was asking the security guard for an epidural!”

Watch for Megan to light up the big screen in This Is 40, which hits theaters Friday, December 21.